The invention relates to a key for locking a cylinder lock, having at least one first surface and at least one second surface and sensing positions provided along the longitudinal extent of the key, wherein at least one code is provided on the first surface and wherein at least one further code is provided on the second surface, the codes comprising control points at the sensing positions that are provided transversely to the longitudinal extent of the key and arranged at certain control heights. The invention also relates to a cylinder lock for a key of this type, and a system made up of a cylinder lock of this type and a key of this type.
Keys with two encoded surfaces which are configured as reversible keys are known from the prior art. Reversible keys are keys, the shaft of which has uniformly arranged profiles, guiding grooves, depressions, elevations or/and notches on both sides. When rotated about its longitudinal axis, a reversible key in each case has the same features thereof and can, therefore, —independently of the side of the key which is pointing upwards—also be introduced into the keyway of the associated lock cylinder in a rotated fashion, which is not possible in the case of a normal key with notches on one side.
As the codes on reversible keys are identical on both sides, the codes are usually read on each side alternately in the lock, in order to reduce the number of sensing elements. In this context, the term “identical codes” means that the codes are the same on the respectively considered surfaces when the key is rotated about its longitudinal axis.
In reversible keys of this type, however, the depiction of one side is sufficient in order to be able to reproduce the key. This is disadvantageous with regard to modern reproduction methods (high-resolution smartphone cameras in combination with 3D printing), as illegal keys can easily be brought into circulation.
Furthermore, in the case of reversible keys with laterally arranged control points, the problem emerges that the control points on both sides of the key must be identical in the sense of the above definition. However, limitations for the realization of the control points at the key tip result: The central position of the tumbler at the key tip cannot be used, as there would otherwise be an increased danger of breakage.